(Reuters) - GlaxoSmithKline (GSK.L) has agreed to sell a clutch of international over-the-counter healthcare brands for 164 million pounds ($263 million) to South Africa's Aspen Pharmacare (APNJ.J), Britain's biggest drugmaker said on Friday.

Net cash proceeds from the transaction are expected to be approximately 135 million pounds and will be returned to shareholders during 2012.